Pneumatic tire tread comprising a plurality of incisions

Abstract

A tread comprises a central zone with a width of between 70% and 80% of the width W of the tread. The central zone comprises one or more circumferential bands, each being delimited by two grooves of a width greater than or equal to 2 mm, and each comprising a contact surface intended to come into contact with the ground and a plurality of transverse sipes distributed evenly in the circumferential direction. Each sipe has, on the contact surface, a width less than 2 mm so as to define a mean circumferential void ratio, which is between 0.5 times and 1.5 times the ratio between a mean thickness (E) of the circumferential band to a mean circumferential radius of curvature (Rc) of the said circumferential band. The sipes divide the circumferential band into a succession of blocks, each having two edge corners intersecting the contact surface of the circumferential band, at least one of the edge corners of said block extending radially by an inclined part forming a chamfer. This inclined part connects the edge corner to a lateral wall of the block so as to generate an offset in the circumferential direction between the said edge corner and the lateral wall of the block.

Description

BACKGROUND[0001]1. Field[0002]The present invention relates to a tire tread comprising a plurality of sipes and associated means for reducing the rolling energy consumption of this tread. The invention relates notably to treads for tires intended to be fitted to passenger motor vehicles.[0003]2. Description of Related Art[0004]Reducing the energy consumption associated with moving a vehicle along is an important objective sought by all motor vehicle manufacturers and constructors. It is often the case that this objective governs the development and marketing of the tires.[0005]In order to reduce this energy consumption, one solution is to reduce the rolling resistance of the tires.[0006]It is known that the rolling resistance of a tire being driven on is connected with the energy losses within the said tire. These energy losses are dependent on the hysteresis characteristics of the rubber compounds used in the tread. These energy losses are also dependent on the deformation cycles e...

AI Technical Summary

Benefits of technology

The patent text discusses a problem with the design of a tire's cuff (circumferential band). The band is typically too flexible at the front of the tire, which can cause the walls of adjacent blocks to separate and widen the gaps before they touch the ground. This results in increased hysteresis energy losses. The patent proposes a solution by inclining the sipes (the gaps between the blocks) in the tire's depth. This reduces deformation of the blocks and ensures better closure of the sipes.

Problems solved by technology

These energy losses are also dependent on the deformation cycles experienced by the tread as the tire is driven on.

Under the action of these various forces, the tread deforms, leading to energy losses through hysteresis.

This deformation of the lateral walls leads to energy losses through hysteresis.

The fact that such a small radius of curvature exists leads to a high degree of flexing of the circumferential band ahead of the contact patch.

This high degree of flexing has a tendency to part the lateral walls of the adjacent blocks and therefore to widen the sipes just before they enter the contact patch, the result of this being to increase hysteresis energy losses.

Thanks to the chamfers, hysteresis energy losses are limited still further.

Hysteresis energy losses are limited even further.

Beyond 45 degrees, the area of contact with the ground and the rigidity of the blocks is reduced excessively and this can ultimately impair the correct operation of the tread.

These non-directional tires do not have a preferred direction of running.

Hysteresis energy losses are therefore limited even more.

The deformation of the blocks is thus limited even further.

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